What seems to be a more consistent play is to put it in an aggro/weapon rogue that can easily deal damage to itself from turn two and with leeching poison immediately heal.
A great high tempo play to deadly/leeching on turn three and drop this, while removing a threat.

Priest is the natural class to put this in with, as if you suffer any fact damage by turn 1 or 2, you can throw out a 3/3 for no mana, in addition to what your usual play would be.

There’s other synergies of course with Paladin, where healing is a side effect of many other cards. However, I do not suggest playing this with Neutral cards that have healing effects. I’ve seen Voodoo Healer thrown out and…no. That’s an awful idea.

Seems pretty good. I’m not sure if Priest will be AS enthusiastic as people think they will for it. I wish this was the 2 mana card Priest is looking for (in theory they heal themselves on turn 2 with hero power and then play this), but you frequently won’t be hurt on 2, so that isn’t consistent enough to work.

That being said, some decks will really like this card. Stapling a 3/3 for zero mana (and a card, which IS relevant, so keep that in mind) will be very appealing, especially with so much lifesteal running around. I’m not willing to call it great immediately, but it will offer some very interesting build and play options. Keep an eye on this card.

This is an arena card dude. In constructed, control decks don’t need this, because the 3/3 stats are rather weak. Playing it free isn’t much value for them anyway. Aggro decks won’t need this because they don’t heal themself, a 3-mana 3/3 is weak, and expensive. It’s probably not the best pick in arena either, but it’s decent. In priest you have the chance to play it on turn 2. That’s it. Not too unbalanced.